The contribution of this project is the development of a probable three dimensional structure of the repeat sequence of the cost protein of the sporozoite stage of the malaria parasite plasmodium falciparum. The structure is an unprecedented right- handed helix, which has twelve amino acid residues per turn and stabilized by extensive hydrogen bonding. From this work, three suggestions have been made regarding the design of vaccine components. Vaccine development is underway in several laboratories. This work has been published in the Proc. Natl. Acad. Sci. 84, 4470 (1987).